A method of infrared heat-processing of nuts (e.g., almonds, Brazil nuts, cashews, hazelnuts, macadamias, pecans, pine nuts, pistachios, walnuts and mixtures thereof) in order to reduce the microorganism level thereof is provided wherein the nuts are sequentially moisturized by application of water and then subjected to infrared radiation, preferably through a series of treatment cycles. Nut treatment apparatus (10) includes opposed banks of infrared heaters (38,40), with plural water application stations (48,50,52) along the length of the heater banks (38,40).